In establishing the course of events, possible cause, and the cure of Karl May's childhood blindness, we have to start with a time sequence:
born 25th February
"I was born neither blind, nor burdened with some hereditary bodily defect." 1843
age 12 months
"Shortly after my birth [I] became seriously ill, lost eyesight and was for full four years in bad health." 1844
age two years
age three years
"I saw nothing...I could only feel, hear, as well as smell the people and surroundings."
age four years
"[My mother] was asked to bring me to Dresden to be treated. This had happened...I learned to see and returned, also for the rest recovered, home."
Normal Development of Vision
Although the baby's eyes remain closed for most of the time immediately after birth, they are sensitive to bright light. At two weeks, the child will pay some attention to large objects in the line of vision, and between two and four weeks will look intently toward the mother's face. At two months, a child can follow an object or light moved from side to side and can do it rapidly and accurately at three months. By this age children are visually alert and particularly interested in nearby human faces.
At six months, children can move their eyes in every direction, can move both eyes together and can immediately focus on small, close objects of interest. Adult movements are followed across the room. At nine month. Children watch the activities of people and animals within three to four meters and by twelve months, out of doors, they watch people, cars, etc. with great interest and will recognize figures approaching from six meters away or more.
At about eighteen months, children enjoy simple picture books, recognizing some items, and by two years will recognize and point to fine details in pictures and familiar adults in photographs once they have been pointed out. From two to three years they will notice small toys immediately at the other end of a room and will point to distant objects out of doors.
From three to four years children can cooperate well in visual testing, using charts.
The brain center for vision is located in the occipital cortex. This brain center needed for cortical connections during early development is impressionable until approximately eight to nine years of age. This means that permanent damage to it, i.e. the center would become incapable or would refuse to acknowledge the images seen with the eyes, could happen if there is a permanent obstacle in transmission to the center during the first decade. The visual system is completely developed and cannot be changed by the time a child reaches age nine.
The first few months of life are the most critical period. Parents would notice and report any abnormality of their baby's eyes - as any unusual appearance like whitish areas or clouding in the front of the eye or in the pupil. Also any unusual movements of the eyes, especially a persistent flickering, so that the eyes do not remain steady when the child is looking at something.
What interferes with normal vision?
Abnormal visual stimulation early in life (newborn to seven years old) could be the result of strabismus (eye misalignment), anisometropia (a difference in the refraction of the two eyes), or deprivation from a droopy eyelid or cataract that "deprives" or blocks the eye from seeing. Amblyopia ("lazy eye") refers to a decreased visual acuity in one eye, when the visual cortex, the area of the brain that processes vision, progressively "tunes out" the input from the weaker eye. Treatment of amblyopia is possible until the age of nine years, when the vision loss becomes essentially irreversible.
Infection of the conjunctiva is caused by various microorganisms (Staphylococcus, Streptococcus, Haemophilus conjunctivitidis, Diplococcus pneumoniae), and also by various viruses. Worrying used to be Conjunctivitis blenorrhoica neonatorum (pussy conjunctivitis of newborn babies), caused by Neisseria gonorrhoeae, which appeared between the first and fifth day after birth. Conjunctivitis pseudomembranacea, caused by Corynebacterium diphteriae, as part of diphtheria, was mostly lethal. Trachoma, a form of conjunctivitis with granular reaction on the inside of eyelids, caused by a virus related to the Ricketsia germ, is of chronic duration which ultimately could lead to permanent blindness from secondary infection of the cornea. There are more pathogens that could cause infection on the conjunctiva, as for example Syphilis or Tuberculosis.
All the previous causes apply also to the cornea. Keratoconjunctivitis phlyctaenulosa used to be a serious eye affliction of childhood's age. So-called Phlyctaena was until recently one of the common causes of blindness in young people. There are many other diseases of the intricate and delicate eye system. People around the baby Karl would have noticed abnormalities - which previously finished in total blindness, like Buphthalmus or Hydrophthalmus (Infantile glaucoma).
Opacities of the crystalline lens, the cataract, could be inborn (Cataracta congenita). Many total cataracts are caused by intrauterine infections (Toxoplasmosis, German measles or other virus infections). Lues or Gonorrhea in the parents could cause inborn cataracts through bacterial toxins. Some chemical or physical influences (alcoholism, damage to the embryo through X-rays) could bring on cataracts in the fetus. There are various types of cataracts (cataracta polaris anterior et posterior; pyramidalis; centralis; totalis; membranacea, perinuclearis or zonularis, coronaria sive coerulea). Total cataracts in small children have to be operated on very early, in already first weeks or months of postnatal life.
"I was not born blind ... shortly after my birth I became gravely ill, lost the eyesight and was in bad health for full four years" Karl May wrote these words in his biography in 1910. This he had to be told later in his life, as he certainly could not have remembered it. People differ in remembering their own earliest memory.
Psychologists today came to the conclusion that very few of the events of early childhood remain in memory. They believe that children lack the cognitive skills required to encode anything but the very simplest experiences. Early memories of people drop abruptly at three to five years. Before that time language, which is so important to memory, is not well enough developed to encode a sequence of happenings.
Some of the visual memories that survive from earlier years are those that are protected from interference, because they have a special importance. They are called 'flashbulb memories', vivid recollections of important events, often stressful ones. Karl May mentions two such events. Both fit into the time slot after his treatment of blindness.
After the sale of the house Karl May was born in, the family moved into another place which had a small pond with frogs behind it. They moved there in April 1845. Karl's mother, Christiane Wilhelmine May, attended a half-year midwifery course at Dresden from the 15 August 1845. Karl was treated in Dresden sometime after this date. One of the first visual memories, rather stressful, was of the smallpox-affected face of his sister. Another impression was the sight and sound of frogs in the following spring and summer of 1846. Earliest memory is of something very concrete, something which can be remembered in terms of visual images or possibly emotional reactions.
Some long-enduring memories are for passages the child heard at an early age many times. Quite often these are little prayers from childhood. The interesting thing about these memories is that they are preserved as they were memorized, in very literal form, in exact wording. Little Karl's grandmother, Johanne Christiane Kretzschmar, and her "Fairy Tale of Sitara", became deeply embedded in his mind.
Into this category belong also the unreasonable learned fears called phobias. Not all become later in life pathological, i.e. interfering with daily activities, as panic (anxiety) disorder, obsessive-compulsory or somatoform disorders. Much of such preoccupying thoughts and subconscious fear is learned during the early years of childhood. In Karl May it was the preoccupation with eyes and vision, expressed vividly in his literary output.
The Loss of Vision
"I have sat in my childhood for hours still and motionless and starred into the darkness of my sick eyes."
"I saw nothing. There were no figures or forms, no colors, neither places or changes in them. I could certainly feel, hear, also smell the persons and objects;"
From these sentences we can deduce that other senses as hearing, smell and touch, of the little boy were fully developed. The initial development of Karl May's vision must have been normal, as he already mentioned that he was born with normal sight. Because most people cannot remember events from before three, or three and a half, years of age, such deprivation of sight must have started before this age. Karl May was three years old in February 1845. The treatment in Dresden happened sometime between September 1845 and March 1846. May also mentioned that he was very sick during the period of his loss of vision: "...shortly after being born I became very ill."
The vision loss during childhood seemed not to leave Karl May with any serious eye damage. On the many photographs of him sometimes he is wearing glasses, and sometimes he is not. The spectacles on the photos of Karl May are not those with thick lenses. There are preserved correction glasses allegedly used by Karl May, in the Radebeul Museum in Germany. The glasses were prescribed for a person who was slightly myopic (shortsighted) and astigmatic, more in the right eye then the left eye.
Xerosis conjunctivae epithelialis
Deficiency of vitamins A and D used to be quite common in the 19th century in children. Both deficiencies start some months after birth. Lack of vitamin A presents itself with eye symptoms (xerophthalmia - a dry and thickened condition of the conjunctiva, which at the beginning resembles crumbled cigarette paper, later looks like dry soap foam, yellowish triangular spots with their base towards the cornea, called Bitot's spots.) The dryness (Xerosis) of the conjunctiva could be the only sign. Vision disturbances are to be found in older children, not in newborn. The child suffers from Nyctalopia - night blindness. Mild forms of xerophthalmia do not spread onto the cornea. Eyelids are closed and swollen.
Gastrointestinal disturbances, diarrhea and insufficient absorption of food accompany deficiency of vitamins A and D. The skin is dry. The child has lower resistance to infections and does not thrive. Bronchitis or bronchopneumonia is common, frequently pyuria (the presence of pus in urine) is found. The child becomes a very sick patient who is not able to see. The prognosis of xerophthalmia, if no ulceration and perforation of the cornea eventuates, is good if therapy is started.
The diagnosis of insufficiency of vitamin A - and vitamin D - with Xerophthalmia, Hemeralopia and Nyctalopia, is quite consistent with the description of his illness by Karl May: "That I shortly after my birth became seriously ill, lost eyesight and was for full four years in bad health, was not the consequence of heredity, but of purely local conditions, the poverty, foolishness and the ruinous medicinal quackery to which I fell victim. As soon as I came into the hands of competent physicians, the eyesight returned to me and I became an extremely strong and resilient youngster."
The "competent physicians" were Dr. Carl Friedrich Haase (1788 - 1865), and Dr. Woldemar Ludwig Grenser (1812 - 1872), Professors of obstetrics and with this discipline connected perinatal care of the newborn.
The theme of blindness in Karl May's writings
The inability to see during the sensitive stage of mental development has left lifelong lasting effect on Karl May. There are very many examples in May's writing on the use of other senses onto which visually impaired have to learn to rely.
Valentine Hauy (1745 - 1822), the son of a weaver, opened the first school for the blind in 1784 in Paris. Hauy had given a coin to a blind beggar in 1771 and was intrigued to observe how he felt the edge to assess its value. The beggar's coin-feeling technique had planted the idea into his mind whether this trick could be used to help blind people "read".
The Westman Sam Barth was recognized by his childhood sweetheart Augusta in the following way: "She grasped his hands and touched carefully his fingers. It was too dark to see anything. Then she felt on his left hand's ring finger something round, hard, covered with flesh. 'My God! This is the ring!' - 'Yes, it is, the silver one!' - It is you! It is you! Is it possible?'"
This is how Old Shatterhand set free Winnetou at night, when he was tied to a tree: "I first had to determine how Winnetou had been fettered. Carefully placing my hand around the trunk, I touched his foot and lower thigh...I discovered that his feet were tied at the ankles. In addition, a strap had been fastened around them and the tree."
Another example from "Der Scout", the original version of Winnetou: "I heard quick steps. A dark figure emerged exactly in front of me, jumped immediately at me and threw me to the ground. The man kneeled on me and put his hands around my neck ... I bent myself upworth and shook him off. He fell down to the side and I quickly attacked him and grasped him by the neck ... He tried to escape me with eel-like movements. However he did not succeed. In the end his movements became slower and weaker, and his hands let go. He laid still...Then I touched him, because it was too dark to find out who he was. What a surprise; I have defeated Winnetou!"
Another example from 'Von Bagdad nach Stambul': "I could not walk [forward] but I could feel first carefully the room whilst crawling with slowly and quietly outstretched tips of my fingers, before I let my body to follow."
In July 1864 Karl May introduced himself as a Dr. med. Heilig, an eye doctor. He even wrote a prescription for an eye ailment. In his first novel 'Das Waldroeschen', published by H.G.Munchmeyer in 1881-1882, the main hero, Dr. med. Karl Sternau, was well versed in the diseases of the eyes. Karl May had to study and use a textbook of ophthalmology in order to describe accurately the various pathological conditions of the eyes: the Staphyloma (a protrusion of the cornea or sclera), Leukoma (a dense opacity of the cornea), Cataract (grey star), and the then standard procedure of cataract removal.
In the first series of novels Karl May had written, the "Die Rose von Ernstthal" and the "Der verlorne Sohn", eye ailments and eye doctors are frequently mentioned. Even later in "Ardistan und Dschinnistan" an eye affliction attracted Karl May's attention: "One can see for example in Egypt everywhere mothers with small children in their arms, whose sick eyes are fully covered with sucking flies, without a thought given by such mothers to chase away these tormenting insect."
Later in life Karl May started to be worried about his eyes again. May blamed tobacco smoking to be detrimental to the eyesight. May was a heavy smoker all his life himself: "Even if not being an eye doctor I can't stop thinking that also his blindness is connected closely with his heavy smoking, and in that I was proven right later." An advice is given to the blind Munedschi, who was able to recognize near statures only as silhouettes with unclear edges: "And therefore I beg you: give up the smoking of tobacco!"
There is a dialog on smoking between the nonsmoker Morgenstern and the heavy smoker doctor Don Parmesan, in 'Vermachtnis des Inka': "Yet the science had proven that one can get from too much smoking the black star, called amaurosis." Amaurosis means partial or total blindness. Karl May did give up smoking, unfortunately it was too late for his health: "I admit that I was the heaviest smoker from all the smokers I used to know. Now I am not any more. It has been by now five years since my Herzle [Klara May] begged me not to smoke so much...I put down the cigar, which I had in my mouth, and said: 'This one was the last in my life; I smoke no more!' ". Fear of blindness was the reason Karl May had given up smoking. Smoking increases risk of vision loss. People who smoke a pack of cigarettes or more per day face two and half times the risk of developing a potentially blinding disease later in life . Smoking is an avoidable risk factor for developing age-related macular degeneration (AMD). Other research has indicated a relationship between smoking and the risk of cataracts. New studies indicated that an increased risk for AMD continued for more than a decade after people had quit smoking.
Already on the 26 November 1893, Karl May wrote to his publisher Fehsenfeld, that because of his eye ailment he visited shortly Leipzig on two occasions . In this connection presumably the following passage from Old Surehand (Vol.I) was written in the summer of 1894: 'I was born a sick and weak child, who still at the age of six crawled on the ground, not being able to stand or run ... I was blind three times ...'
Karl May answered in 1897 a letter from a person in the Institute for Blind in Alsace: 'As it looks as you do not know just as yet the three volumes of Old Surehand, I am sending them to you as a present, from your Old Shatterhand. You will find out from the first volume, that I also was blind, and therefore know very well what a marvelous God's gift is denied to the dear students of your Institute...'
Medically speaking Karl May's case of blindness is an intriguing one. All the circumstantial evidence - as described by Karl May in his literary output - testifies for his early childhood experience of loss of vision: the depicted senses of touch, listening, smell, the nocturnal scenes.
Karl May also suffered from subconscious fear of blindness - the suppressed "Long-lasting memory" - expressed in his preoccupation with eye doctors, eye diseases and the treatment of eye ailments he was quite familiar with.
From the normal development of vision in the newborn it is known that a certain period of time is necessary after birth to establish the visual input to reach and establish itself in the cortical center. We know that Karl May was not born with cataracts (he did not mentioned any operation to remove them, nor did he need to wear thick lens glasses). May did not suffer from any damaging eye ailment which would affect his cornea causing serious visual impairment in later life (the preserved spectacles show only mild myopia and astigmatism).
Memory is an important factor in establishing the course of event. The majority of people do not remember events before the age of three years of life. The Karl May's statements "I was born neither blind..." and "Shortly after my birth [I] became seriously ill, lost eyesight..." have to be based not on personal experience but on what he had been told by other people, most probably his family members. This only confirms that there was enough of time to establish the vital connection between the eyes and the cortical center.
Karl May's first memories: "I saw nothing...I could only feel, hear, as well as smell the people and surroundings" had to come at an age when his eyes have already been affected. The many Fairy Tales narrated to him by his grandmother belong to a characteristic long-lasting memory. It became deeply impressed in May's mind in a similar fashion as we remember forever the prayers taught to us as children. Later on Karl May in his creative artistic way identified his grandmother with the book Hakawati.
Fairy Tales were his life elixir: "I myself must change into a Fairy Tale, my own I".
In this sense, as a Fairy Tale, May told his life story to a young admirer, Maria Hannes: "... that Karl May was born on the 25 February 1842 in a small village in Upper Bavaria ... He had many brothers and sisters, his parents were poor people - very poor. The small Karl was a visibly weak child - almost paralyzed - with very sick eyes - in short - hardly able to survive. How could his father, who had to struggle so hard with misery and distress, afford an expensive treatment and to take care to make the little sickly body stronger? One spring morning, when the little Karl, much attracted by sunshine, crawled (as he could not walk) in front of the house to follow the merry play of joyous children with his half-blind eyes - then - suddenly appeared from around the corner a fast coach with four horses in sharp trot and rushed down the narrow village street. Screaming the children jumped away in all direction, no one thinking about the sick Karl May. Indeed, they did not remember him until they found him bleeding and unconscious on the ground. - The lonely man in the back seat of the coach got out in distress and helped to carry the poor child into the house - where they examined him and found serious injuries. There was no way to provide sufficient care and cover the expensive cost in the house of his parents! The stranger, an Austrian nobleman, in all reality, understood this and let the injured to be transported to the city - into a good hospital where he was excellently looked after. There he underwent also an eye operation with the best result, and left the hospital fully recovered and strong, more than he was until then."
May was telling a Fairy Tale, talked about Upper Bavaria, because he had to cover up his origin. He wanted apparently to keep Maria Hannes away from Hohenstein and Ernstthal; there she would discover the whole sad part about his imprisonment, etc. May's early childhood blindness - even if poetically made nicer - is in no case a Fairy Tale. In the 'Rose from Ernstthal' (from 1874) he wrote: "The women arrived only in the afternoon to the doctor [to Chemnitz, about 15 km away from Hohenstein-Ernstthal]. He examined carefully the diseased eyes and then shook his head. The medical knowledge at that time did not reach yet the stage of development at which it is now; there were quarrels about the various doctrines which did not reach yet the experience that the best art of a physician is to remove obstacles and support the nature. People were dabbling in various philosophies and only seldom a gifted head dared to break through the dam of the customary medicinal methods. And so the blind received after final head shake a cooling ointment with a solution of a stone from Galizia and was afterwards dismissed with some comforting words."
"In no time the inquisitive landlady found out that he is a doctor and travels to Dresden to treat there a distinguished blind person. Encouraged by this discovery she told him about Augusta and pleaded to be allowed to bring the girl there."
The eye doctor from Chemnitz could not help - the eye doctor in Dresden can help! The healing of this fictitious blindness in connection with Dresden is very autobiographic, after all May was cured there in the main city by competent doctors Haase and Grenser.
The first visual memories, the so called 'flashbulb memories' described by Karl May (the face of his sister afflicted with smallpox and the frogs in the pond) could be localized in time. They come from the winter and spring/summer of 1846, the time of May's treatment in Dresden.
"[I] was for full four years in bad health." It was not only the visual impairment, but also a general illness. Yet both conditions were cured with success sometime between September 1845 and March 1846. The treatment did not involve any surgical intervention on the eyes. After considering and excluding other possibilities there seems to be only one conclusion: Karl May suffered from vitamin A and D deficiency as a child.
As always there is a book to be found dealing with the subject. Dr.Oliver Sacks, Professor of Neurology at the Albert Einstein College of Medicine, New York, published "An Anthropologist on Mars." In it is a chapter 'To See and Not See' which describes the tribulations of people who had to learn to see - just as Karl May had written: "I learned to see and returned, also for the rest recovered, home."
On the evidence at hand there seems to be no doubt about the fact that Karl May was visually impaired as a child - in his own words he was "blind". There is no reason not to believe what Karl May had written in his biography. He also wrote that he had heard "voices", which many found hard to believe. Yet there is an explanation for it as well.
The Two Hidden Meanings
There are two sentences Karl May wrote in his biography, which had never been interpreted.
(1) "Als ich sehen lernte..." ['When I learned to see'] We who were born sighted can hardly imagine the confusion of visual objects and meanings after a period of blindness. When we open our eyes in the morning it is into a world we have spent a lifetime learning to see. In someone who had little more than an infant's visual experience, there are no visual memories to support a perception. The retina and optic nerve are active, transmitting impulses, but the brain could make no sense of them. In neurological term the optical center is agnostic. A child's brain has the plasticity to adapt Learning to see demands a radical change in neurological functioning and, with it, a radical change in psychological functioning, in self, in identity.
This simple statement by Karl May - 'When I learned to see' - gives credence to the fact that he could not see previously.
(2) "Nur wer blind gewesen ist..." ['Only who was blind...'] Blindness has a positivity of its own. Other perceptual-cognitive processes develop. World of its own comes into existence. Adults often become depressed after regaining vision. However adults are not on the same starting line, neurologically speaking, as children, whose cerebral cortex is equipotential - equally ready to adapt to any form of perception. Karl May had the luck to have a caring and understanding grandmother who developed his inner world, from which he never completely broke off later in life. It has been known that some blind people refuse an operation to bring their vision back. They prefer to live in the world of their own.
It is a good medical practice to believe what the patient has to say. When Karl May wrote his biography in 1910 he mentioned the medical problems that frightened him in the past - his early blindness, the amnesia and hallucinations. Karl May did not find an explanation of what happened to him. This however does not justify saying he was not telling the truth.
A mother seeking medical attention for her child, who is suffering from Vitamin A deficiency, blindness and malnutrition (photo from Nepal) - Australian Doctor, 29 October 1993, p.57.
Please click on the hyperlinked reference numbers to return to your place in the text.
 Karl May: 'Mein Leben und Streben.' Olms Prese Hildesheim - New York 1997, p.16.
 In 
 In , p.31.
 In , p.20.
 'Growth and development of young children.' Department of Social Security, Commonwealth of Australia, Canberra ACT 1981, pp.11-12.
 Florida Eye Institute, Vero Beach, Dr.Minotty: 'Amblyopia.' 1999.
American Academy of Ophthalmology, Washington DC, 'Eyenet' 1997.
New England Eye Center: 'Pediatric Eye Disorders - Amblyopia.' Columbia/HCA 1999.
The Nemours Foundation, KidsHealth.org.: 'Ophthalmology.' 1999.
 Mentioned as a possible cause of Karl May's childhood blindness in: Asbach,G.: 'Das medizinische Wissen Karl May's in den Amerika banden.' Med.Diss. Dusseldorf 1972.
 Kurz, J: 'Zaklady ocniho lekarstvi (Ophthalmology).' Praha 1953.
 In 
 Kimble,G.-Garmazy,N.-Zigler,E.: 'Principles of Psychology.' New York 1984, p.194.
Atkinson R.-Hilgard E.-Atkinson R.-: 'Introduction to Psychology.' Harcourt Brace Jovanovich Inc., New York 1983.
 In , pp.14-16, 19-20.
 In , p.30.
 In , pp.526-527.
 In , p.30.
 In , p.31.
 In , p.16.
 Rods and Cones are retinal cells involved in photoreception. Lack of Vitamin A (Retinol) diminishes their function, in particular at dusk.
 In , p.16.
 In , p.337 - note 21.
 Harder, Ralf: 'Die Erblindung - eine entscheidende Phase im Leben Karl Mays.' Mitteilungen der Karl-May-Gesellschaft (M-KMG), Nr.68/1986; pp.35-38.
 Sakula, A.: 'That the blind may read.' Journal of Medical Biography 1998; 6:21-27.
Leavesley, Jim: 'Men who led the way for the blind.' Australian Doctor, 7 May 1999, pp.94-95.
 Karl May: Deutsche Herzen - Deutsche Helden, Dresden 1885-1888, Lfg.42, S.994. Compare: Ralf Harder: Karl May und seine Munchemeyer Romane - Eine Analyse zu Autorschaft und Datierung. Ubstadt 1996, S.67f.
 Karl May: Winnetou I, Freiburg 1893, p.249.
 Karl May: Der Scout. In: Deutscher Hausschatz in Word und Bild. Verlag Friedrich Pustet, 15 Jg. 1888/89, No.38, p.600 and 602. Compare: Ralf Harder: 'Die Erblindung - eine entscheidende Phase im Leben Karl Mays.' Mitteilungen der Karl-May-Gesellschaft N.68/1986, pp.35-38.- "By touching only to recognize a completely unknown person could be done only by a blind individual, never a sighted one. The only exception is by someone who learned the world first by touching, listening, smelling and tasting, and recovered sight afterwards. Because May was not blind when he wrote this section of the 'Scout', he had to be blind as a child. People - who always had good eyesight - would have written as follows: 'He laid still. The moonlight fell on the face of the Indian. What a surprise; I have -- defeated Winnetou!'
 Karl May: Von Bagdad nach Stambul. Freiburg 1892, p.430.
 Karl May: Ardistan und Dchinnistan I. Freiburg 1909, p.76.
 Karl May: Am Jenseits. Freiburg 1899, p.119.
 Karl May: Das Vermachtnis des Inka. Stuttgart 1895, p.88
 Karl May: Winnetou IV. Freiburg 1910, p.274.
 Compare: Fritz Maschke: Karl May und Emma Pollmer. Bamberg 1973, p.59.
 Journal of the American Medical Association, October 9, 1996.
 In .
 Karl May: Old Surehand I. Freiburg 1894, p.411 f.
 Volker Griese: 'Karl May - Stationes eines Lebens.' Sonderheft der KMG, No.104/1995, under March 20,1897.
 Karl May: Mein Leben und Streben. Freiburg 1910, p.138. Compare: Ralf Harder: Kara Ben Nemsi und der Wolf. Internetfassung 1998.
 Manuscript by Marie Hannes. Quoted by Steimetz und Sudhoff, in: Leben in Schatten des Lichts. Bamberg 1997, p.87 f.
 Karl May: Die Rose von Ernstthal. In: Deutsche Novellen-Flore. Neusalza 1874, p.202.
 Karl May: Die Rose von Ernstthal. As in , p.203.
 Sacks O.: 'An Anthropologist on Mars.' Picador edition by Pan Macmillan Australia 1995. - This book is a must for anyone interested in the problem of Karl May's blindness. It has to be read to understand the connection between touch and sight, the visual - cortex axis, the impressions of tactile, auditory and olfactory inputs. Prof.Oliver Sacks is also the author of "The Man who Mistook his Wife for a Hat", another interesting medical study.
 Karl May: Mein Leben und Streben. Freiburg 1910, p.20.
 Karl May: Mein Leben und Streben. Freiburg 1910, p.32.
 Marius von Senden in his classic book 'Space and Sight' (published 1932) reviewed every published case of people regaining sight over a three-hundred-year period. He mentioned the case of two children whose eyes had been bandaged from an early age, and who, when the bandages were removed at the age of five, showed no reaction to this, showed no looking, and seemed blind. They did not know how to use their eyes.
 Karl May: Mein Leben und Streben. Freiburg 1910, p.31.
 Dr.William E. Thomas: Karl May and D.I.D.
 Johannes Zeilinger: 'Autor in Fabula.' Med.Dissertation, Leipzig 1999.
I thank Mr.Ralf Harder who made me aware of important research material used in this study.